Method of transporting finely comminuted solids



July 17, 1956 M, M. CUNNINGHAM 2,755,143

METHOD OF TRANSPORTING FINELY COMMINUTED SQLIDS Filed July 11, 1955INVENTOR.

ATTORNEY United States Patent METHOD OF TRANSPORTIN G FINELY COMMINUTEDSOLIDS Marion M. Cunningham, Providence, R. L, assignor to United StatesRubber Company, New York, N. Y., a corporation of New Jersey ApplicationJuly 11, 1955, Serial No. 521,066

2 Claims. (Cl. 302-66) My invention relates to a method of transportingfinely comminuted solids through a collapsible hose.

It has heretofore been considered necessary in transporting finelycomminuted solids through a collapsible hose to maintain the hose at aninternal pressure above atmospheric pressure to hold the hose expanded.

I have found that such is not necessary and that, in accordance with myinvention, finely comminuted solids can be transported more efficientlythrough a collapsible hose by suction if the comminuted solids are firstaerated and then positively introduced into the hose.

In accordance with my invention, I use a collapsible hose of suchflexibility that the hose will collapse at least 50% but not more than95% under a differential pressure of approximately atmospheric pressure.I introduced the finely comminuted solid, which has been previouslyaerated, into one end of this collapsible hose by means of a pump andsimultaneously therewith I apply suction to the other end of the hose bymeans of a second pump secured thereto and operated at a volumetric rategreater than that at which the comminuted solid is introduced into thehose by the first mentioned pump.

Under such conditions of operation, I have found that the comminutedsolid will move through the hose more or less in batches with the hosepartially collapsed between the batches.

One advantage of my method over those heretofore used is that a muchsmaller volume of air or gas need be mixed with the comminuted solids inthe transportation thereof and that, therefore, the problem ofseparating the comminuted solid from the gas or air in the ultimate useor storage thereof is materially reduced.

Another very important advantage is that as the batches of comminutedsolids move through the hose there is a constant expanding andcollapsing of the hose immediately following the moving batches whichprevents the caking of the solids on the interior wall of the hose.

Other objects and advantages of my invention will become apparent fromthe following description when read in conjunction with the accompanyingdrawing which is an elevational view, partly in section, of apparatusfor transporting comminuted solids in accordance with my invention; theapparatus being shown as used in emptying a collapsible container of thegeneral type shown in my United States Patent No. 2,612,924.

Referring to the drawing, the finely comminuted solid flows by gravityfrom the container C, supported on an emptying device E of the typegenerally shown in my copending application Serial No. 516,419, filedJune 20, 1955, through sleeve valve S into a pipe and across adiagonally extending piece of porous fabric 13 which is clamped betweenthe pipe 10 and a lower supporting plenum chamber 14. Air or gas under acomparatively low pressure is admitted through a pipe 14a into theplenum chamber 14 under the fabric 13 and passes up through theinterstices of the fabric 13 and mixes with Patented July 17, 1956 andaerates the finely comminuted solid passing across the fabric to therebyincrease the fluidity thereof.

From the fabric 13, the aerated comminuted solid passes to a pump 15,preferably a constant flow pump, and is fed thereby into one end of acollapsible hose 16 which is attached to the discharge side of the pump15.

The hose 16 is of a gas impervious construction and has a circular crosssection when expanded. In accordance with the invention, the hose is ofa flexible construction such that the hose will collapse at least 50%but not more than under a diiferential pressure of approximatelyatmospheric pressure. Expressed in another manner, under a differentialpressure of approximately atmospheric pressure, the hose will collapsesuch an amount that the internal cross sectional area of the hose isbetween 50% and 5% of the cross sectional area of the hose whenexpanded. A conventional woven, rubber lined fire type collapsible waterhose can be used for the hose 16. I prefer however that the interiorsurface of the hose be smoother than that of the usual conventional firehose.

Simultaneously with the feeding of the aerated comminuted solid into thehose 16 by the pump 15, a second pump 17, also preferably a constantflow pump, secured to the other end of the hose is operated at avolumetric rate greater than that at which the comminuted solid is beingfed into the hose by the pump 15 to apply suction to the hose. Under theinfluence of this suction applied by the pump 17, the aerated comminutedsolid moves through the hose more or less in batches B with the hosepartially collapsed between the batches as illustrated in the drawingand is discharged through the pump 17. For most eflicient operation, thepumps should be operated to provide a lineal discharge of 300 or morefeet per minute of the aerated comminuted solid.

If pumps of the same rating are used for pumps 15 and 17, the differencein volumetric rate between the pump 15 and the pump 17 may be obtainedmerely by operating the pump 17 at higher revolutions per minute. If apump of a higher rating is used for the pump 17 than for the pump 15,then of course the two pumps could be operated at the same revolutionsper minute.

In practicing my invention, very'little air or gas need be mixed withthe comminuted solid. A ratio of 10 parts by volume of air or gas to onepart of solid is usually sufficient. Consequently, the problem inherentin methods heretofore used of separating the solids from a large volumeof air is essentially eliminated. The problem of caking of thecomminuted solids on the wall of the hose, which is inherent in methodsin which the hose is maintained under above atmospheric pressure isnonexistent in my method, as the walls of the hose are constantly flexedby the expansion and collapsing of the hose as the batches of comminutedsolids move through the hose.

My method can be used to transport solids in all directions, i. e.,horizontally, vertically, etc. There is, however, some limitations as tothe particle size of the comminuted solids which can be efiicientlytransported by my method. Generally speaking the comminuted solidsshould be finer than 20 mesh and preferably finer than about 65 mesh,though particles of larger size can be conveyed if the major portion ofthe solids are of a particle size as defined. Among some of thematerials which can be conveyed when in a finely comminuted dry stateare: Portland cement, special cements, limestone, dolomite, magnesite,silica, clays including bentonite, barites, gypsum, cryolite, bauxite,phosphate rock and apatite, iron ore, talc, coal, quick lime, hydratedlime, magnesia, alumina, soda ash, sodium phosphate, litharge,anhydrite, ammonium sulfate, fly ash, furnace and kiln flue dust,

3 bulk resins and plastics, sugar, and t'arinaceous material such asbread and cake flours.

The term aerate" is used herein in its generic sense to denote mixing ofthe comminuted solid with various types of gases, including air. In mostinstances it is contemplated that the gas will be air but where thecomminuted material being transported is subject to contamination by orpresents a hazardous condition in the prescnc of air, an inert gas, suchas nitrogen, may be used 7 to aerate the comminuted solid.

Having thus described my invention, what I claim and desire to protectby Letters Patent is:

l. The method of transporting a finely comminuted solid comprising,aerating the finely comminuted solid, pumping the aerated comminutedsolid by means of a pump into one end of a collapsible hose havingflexibility such that the hose will collapse at least 50% but not morethan 95% under a differential pressure of substantially atmosphericpressure, and simultaneously therewith applying suction to the other endof the hose by a pump secured thereto and operated at a volumetric ratein excess of that at which the aerated comminuted solid is pumped intothe hose.

2. The method of transporting aerated finely comminuted solidcomprising, pumping the aerated comminuted solid by means of a pump intoone end of a collapsible hose having a flexibility such that the hosewill collapse at least 50% but not more than 90% under a differentialpressure of substantially atmospheric pressure, and simultaneouslytherewith applying suction to the other end of the hose by a pumpsecured thereto and operated at a volumetric rate in excess of that atwhich the aerated comminuted solid is pumped into the hose.

No references cited.

1. THE METHOD OF TRANSPORTING A FINELY COMMINUTED SOLID COMPRISING,AERATING THE FINELY COMMINUTED SOLID, PUMPING THE AERATED COMMINUTEDSOLID BY MEANS OF A PUMP INTO ONE END OF A COLLAPSIBLE HOSE HAVINGFLEXIBILITY SUCH THAT THE HOSE WILL COLLAPSE AT LEAST 50% BUT NOT MORETHAN 95% UNDER A DIFFERNTIAL PRSSURE OF SUBSTANTIALLY ATMOSPHERICPRESSURE, AND SIMULTANEOUSLY THEREWITH APPLYING SUCTION TO THE OTHER ENDOF THE HOSE BY A PUMP SECURED THERETO AND OPERATED AT A VOLUMETRIC RATEIN EXCESS OF THAT AT WHICH THE AERTED COMMINUTED SOLID IS PUMPED INTOTHE HOSE.